Aerodynamic Flow Sensing with Elastic Microfence Structures

Saini, Aditya; Kim, Taeyang; Cui, Zheng; Schuessler, Benjamin; Palmieri, Frank L.; Lin, Yi; Connell, John W.; Jiang, Xiaoning; Zhu, Yong; Gopalarathnam, Ashok; Wohl, Christopher J.

doi:10.2514/6.2017-0479

Cited by 2 publications

(1 citation statement)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Micro-fences have been successfully shown to be capable of sensing flow reversal on a flat-plate wind tunnel setup using optical transduction [18]. Although optical measurement techniques have shown potential in laboratory investigations, the technology is still not entirely feasible for practical applications on aircraft wings due to the complicated camera setup required.…”

Section: Flow Separation and Stallmentioning

confidence: 99%

Airfoil Flow-Separation and Stall Detection Using Surface-Mounted Pitot Tubes

Aleman

Saini

Gopalarathnam

2017

35th AIAA Applied Aerodynamics Conference

Self Cite

View full text Add to dashboard Cite

A two-probe sensor concept for the detection of flow separation is introduced in this research. The conventional flight envelope of transport-type aircraft follows the linear aerodynamic region where the flow remains attached and the boundary layer is thin. However, as the angle of attack is increased, the adverse pressure gradient on the surface causes the flow to lose momentum and eventually separate resulting in significant loss of lift, leading to aircraft stall accidents. In this work, a real-time pressure measurement system is explored that consists of two opposite-facing pitot tubes mounted on the surface of an airfoil to detect flow separation or stall. Experimental investigations were conducted in the subsonic wind tunnel at North Carolina State University (NCSU) to assess the effectiveness of such a technique. Tests were performed at three different Reynolds numbers (0.39, 0.5, and 0.56 million) on a 12%-thick low-Reynolds number airfoil in the NCSU subsonic wind tunnel. An estimate of the separation-point location was obtained from the flat-lining behavior or constant pressure region on the airfoil surface pressure distribution to confirm the presence of separation region at the pitot tubes location. The results showed that the pressure difference between the forward and backward-facing pitot tubes can be successfully used to determine the location of the separation point as the angle of attack changes. For any airfoil, the location of the separation point on the airfoil surface can be correlated with the stall angle of attack. Hence, mounting the pitot tubes at a chordwise location that corresponds to flow separation at stall can serve as an effective technique for stall detection. The two-probe concept holds the potential to be further developed into an entirely self-contained device that can be externally mounted on any aircraft system.

show abstract

Section: Flow Separation and Stallmentioning

confidence: 99%

Airfoil Flow-Separation and Stall Detection Using Surface-Mounted Pitot Tubes

Aleman

Saini

Gopalarathnam

2017

35th AIAA Applied Aerodynamics Conference

Self Cite

View full text Add to dashboard Cite

show abstract

Leading-Edge Flow Sensing for Aerodynamic Parameter Estimation

Saini

Gopalarathnam

2018

AIAA Journal

Self Cite

View full text Add to dashboard Cite

SAINI, ADITYA. Leading-Edge Flow Sensing for Aerodynamic Parameter Estimation. (Under the direction of Dr. Ashok Gopalarathnam.) The identification of inflow air data quantities such as airspeed, angle of attack, and local lift coefficient on various sections of a wing or rotor blade provides the capability for load monitoring, aerodynamic diagnostics, and control on devices ranging from air vehicles to wind turbines. Real-time measurement of aerodynamic parameters during flight provides the ability to enhance aircraft operating capabilities while preventing dangerous stall situations. This thesis presents a novel Leading-Edge Flow Sensing (LEFS) algorithm for the determination of the air-data parameters using discrete surface pressures measured at a few ports in the vicinity of the leading edge of a wing or blade section. The approach approximates the leading-edge region of the airfoil as a parabola and uses pressure distribution from the exact potential-flow solution for the parabola to fit the pressures measured from the ports. Pressures sensed at five discrete locations near the leading edge of an airfoil are given as input to the algorithm to solve the model using a simple nonlinear regression. The algorithm directly computes the inflow velocity, the stagnation-point location, section angle of attack and lift coefficient. The performance of the algorithm is assessed using computational and experimental data in the literature for airfoils under different flow conditions. The results show good correlation between the actual and predicted aerodynamic quantities within the pre-stall regime, even for a rotating blade section. Sensing the deviation of the aerodynamic behavior from the linear regime requires additional information on the location of flow separation on the airfoil surface. Bio-inspired artificial hair sensors were explored as a part of the current research for stall detection. The response of such artificial micro-structures can identify critical flow characteristics, which relate directly to the stall behavior. The response of the microfences was recorded via an optical microscope for flow over a flat plate at different freestream velocities in the NCSU subsonic wind tunnel. Experi

show abstract

Aerodynamic Flow Sensing with Elastic Microfence Structures

Cited by 2 publications

References 13 publications

Airfoil Flow-Separation and Stall Detection Using Surface-Mounted Pitot Tubes

Airfoil Flow-Separation and Stall Detection Using Surface-Mounted Pitot Tubes

Leading-Edge Flow Sensing for Aerodynamic Parameter Estimation

Contact Info

Product

Resources

About